Steel components in bending ? Column bases

Post feet can be designed as hinged or embedded, which has a significant impact on the price of the steel structure and foundations.

In the building industry, it is common practice to weld a plate to the end of a column and to connect it to the foundation by means of two or even four anchor rods, but placed at or near the axis of the same column. This type of column foot is then considered nominally articulated, and this design remains sufficient as long as the rotations are not too great. In the opposite case, when greater rotations are required, other devices such as grains or clevises with hinge pins can be used, the aim being to achieve a bearing design that conforms to the assumptions made in modeling the structure.

Eurocode 3 makes it possible to calculate the resistance of column feet subjected to tensile or compressive stress using the component method, which in this case is fairly easy to use. The justification of the articulation hypothesis, made necessary by the Eurocode, is based on constructive provisions that were already present in the French rules (Lescouarc'h's work...). for example). The first part of this article deals with the design and calculation of articulated column feet.

When it becomes difficult to comply with ELS displacement criteria (e.g. presence of an overhead crane), it is sometimes common to use embedded column feet. The resistance of embedded column feet is then calculated using the component method, which is no more complex to use than traditional methods. The requirement to justify that these attachments can be modeled as rigid does, however, give rise to some difficulties. The second part of this article deals with the case of column feet embedded in end plates.

For each of these two parts, an example illustrates the approach.